Pie mash and liquor is a traditional London dish that goes back to the 1800's. Each pie and mash shop has their own family recipe that they will never divulge. Recipes are closely guarded secrets, particularly for the parsely liquor. The pies have a type of puff pastry on top with a different softer pastry underneath that must not be overcooked. Whilst you could try to make this dish at home its best to find a pieshop or order online and enjoy the real thing! Not forgetting to add lots of chilli vinegar.